Steerable delivery system and components

Abstract

Devices, systems and methods are described herein to provide improved steerability for delivering a prosthesis to a body location, for example, for delivering a replacement mitral valve to a native mitral valve location. Disclosed are a number of features that can improve steerability or release of the prosthesis into the body location.

What is claimed is: 
     
       1. A delivery system for delivering an expandable implant to a body location, the delivery system comprising:
 an outer sheath assembly comprising an outer shaft having an outer lumen and a proximal end and a distal end, wherein the distal end of the outer sheath assembly comprises a capsule, the capsule comprising an implant retention area configured to retain the expandable implant in a compressed configuration; and 
 an inner assembly located within the outer lumen, the inner assembly comprising an inner shaft having an inner lumen and a proximal end and a distal end, wherein the inner assembly comprises an inner retention member configured to be releasably attached to the expandable implant; and 
 a steerable sheath surrounding a portion of the outer sheath assembly, wherein the steerable sheath comprises a plurality of circumferential slots separated by a longitudinal spine, a steerable sheath lumen, a longitudinal cut out formed along the longitudinal spine, a lumen attached into the longitudinal cut out, a proximal pull wire attached at a proximal bend location and passing through the steerable sheath lumen, and a distal pull wire extending through the lumen attached into the longitudinal cut out and attached at a distal bend location distal to the lumen attached into the longitudinal cut out, 
 wherein the capsule is formed of collapsible material such that the capsule can be withdrawn into the steerable sheath, 
 wherein a proximal force on the proximal pull wire forms a first bend at the proximal bend location and a proximal force on the distal pull wire forms a second bend at the distal bend location, and 
 wherein when a proximal force is applied to the distal pull wire, the delivery system is only bent at the distal bend location. 
 
     
     
       2. The delivery system of  claim 1 , wherein the inner shaft comprises an outer retention ring slideable along the inner shaft and at least one tab, wherein the at least one tab is moveable between a radially flared position and a radially compressed position, wherein when the at least one tab is in the radially compressed position, the outer retention ring can slide over the at least one tab, and wherein when the at least one tab is in the radially flared position, the outer retention ring is prevented from moving proximally over the at least one tab. 
     
     
       3. The delivery system of  claim 1 , wherein the proximal pull wire comprises a pair of proximal pull wires, wherein the pair of proximal pull wires are circumferentially spaced apart at a proximal portion of the steerable sheath and are circumferentially adjacent at a distal portion of the steerable sheath. 
     
     
       4. The delivery system of  claim 1 , wherein the proximal pull wire comprises a pair of proximal pull wires, wherein the pair of proximal pull wires are circumferentially adjacent at a proximal portion of the steerable sheath and are circumferentially spaced apart at a distal portion of the steerable sheath. 
     
     
       5. The delivery system of  claim 1 , wherein the outer sheath assembly comprises an axial runner containing an axial wire having an untensioned configuration and a tensioned configuration, wherein the outer sheath assembly can bend when the axial wire is in the untensioned configuration and wherein the outer sheath assembly cannot bend when the axial wire is in the tensioned configuration. 
     
     
       6. The delivery system of  claim 1 , wherein the outer sheath assembly comprises a spiral backbone having a plurality of circumferentially extending slots along a length of the outer sheath assembly, wherein the spiral backbone is longitudinally thicker at a first circumferential portion than at a second circumferential portion, and wherein the first circumferential portion is approximately a first circumferential half and the second circumferential portion is approximately a second circumferential half. 
     
     
       7. The delivery system of  claim 1 , wherein the outer sheath assembly comprises a longitudinally extending slot on at least a portion of an inner surface of the outer sheath assembly, and wherein the inner retention member comprises a tab configured to mate with and follow along the longitudinally extending slot. 
     
     
       8. The delivery system  claim 1 , wherein the inner retention member comprises a plurality of longitudinally extending slots, and wherein the inner retention member comprises a plurality of rotatable flaps each configured to rotatably cover one of the plurality of longitudinally extending slots. 
     
     
       9. The delivery system of  claim 1 , wherein the outer sheath assembly further comprises an outer retention ring configured to cover the inner retention member, wherein the outer retention ring is attached to the outer sheath assembly with at least one suture, wherein an initial retraction of the outer sheath assembly uncovers the inner retention member from the outer sheath assembly while the outer retention ring remains over the inner retention member, and wherein further proximal retraction of the outer sheath assembly provides tension on the at least one suture to uncover the inner retention member from the outer retention ring. 
     
     
       10. The delivery system of  claim 1 , wherein the outer sheath assembly comprises a distal section having a plurality of longitudinally spaced apart circumferential rings. 
     
     
       11. The delivery system of  claim 1 , wherein the capsule comprises an outer polymer layer, a high melting temperature polymer layer radially inwards of the outer polymer layer, a metal layer radially inwards of the high melting temperature polymer layer, and a liner radially inwards of the metal layer, wherein the high melting temperature polymer layer comprises a polymer layer having a melting temperature of at least 150° C. 
     
     
       12. The delivery system of  claim 1 , wherein the capsule comprises a flared distal section. 
     
     
       13. The delivery system of  claim 1 , wherein an outer diameter of the capsule tapers from its distal end to its proximal end.